High-temperature conduit



Vinatentetl July 1, 19.47

'UNITED Nsrn'rizsV `PA'rraN'r oFFlcE HIGH- TEMPERATURE CONDUIT Louis Joe Weber, Borger, Tex., assignor to Phillips Petroleum Company, a corporation of Delaware Application November 13, 1944, Serial No. 563,213

11 claims. l

In one of its more speciilc as- (ci. 13s-c4) Y 2 minimizing the discomfort to be inflicted upon the operating personnel, as well.

For example, one particular application for which my improvement'has great utility is in a process for treating hydrocarbonawherein it is necessary tocool the eilluent from a reaction 4 vessel from 1500 F. down to about 850 F., at a bon steel, for example, which will satisfactorily bear the pressure stresses as long as the temperature .of theshell is not excessive; and (3) a layer of suitable insulating material interposed between the two concentric shells to insure maintenance .of the outer shell temperature below the allowabley limit.

In tlie past, many alloy steels have been developed for use in high temperature applications, such as in steam superheaters, petroleum cracking stills etc. These alloyswere developed. to

' answer two speciilc problems. One problem is in the overcoming of rapid corrosion effect oi high temperature steam and/or organic gases upon equipment constructed of the early common types of steel. The second advantage gained by the introduction of these special alloy steels was an improvement in tensile strength at elevated temperatures.

Whilelthe advantage of the special alloy steels is greatlinY regard to corrosion resistance, the improvement in strength characteristic as compared to ordinary steels is not proportionate to the increased cost of the alloy materials. The result is that equipment for high temperature application (where high pressures are usually corollary) is designed to employ either the alloy materials at great money expense, or the ordinary steels at a lesser expense but a still `considerable one and with the disadvantage of great bulk in the structure.

`In my improved construction, the vexpensive corrosion-resistant alloy materials maybe used sparingly with maximum benefit. The stressbearing portion of the structure is protected from both high temperature and corrosive action, so that the less costly common steels can b e used without undue sacrifice with respect to strength, bulk or cost of the equipment to be fabricated. A further advantage is realized in that less heat is lost from the system per unit of time, withxthe dual effect of conserving the heat energy and sustained pressure of approximately pounds per square inch. The required cooling iscarried out in a heat exchanger in which the hot gaseous material is passed around a number of pipes containing water (steam) as a coolant. The gases to be cooled contain various hydrocarbon vapors,

and often an appreciable quantity of sulphur, in

which latter case the corrosive action is especially severe. A

On the basis of results obtained `in an experimental cooler incorporating my improved construction, the indicated cost of the cooling unit and adjacent piping for a commercial application would be but a fraction of that which .would be incurred in conventional fashion, or if available commercial heat exchangers were to be modiiled for the purpose.

A principal object of my invention is to provide a relatively inexpensive structure for the handling of extremely hot gases and vapors.

.fi more specic object is to make practical the use of ordinary carbon steels for the stress-bearing members in an application where theconditions of temperature and corrosion have heretofore required the use of more expensive special alloy steels.

A further object is to reduce the eiect of diiferential expansion in the stressed portions of piping systems by holding the maximum temperature of those parts well below the values obtaining in the case of conventional structure in the same hightemperature service.

It is an object to reduce the amount of heat lost to the atmosphere in a system of the sort herein described, with a consequent increase in ythe amount of useful by-prcduct heat recovered, in the cooling system.

Another object is to provide, in a unit of the nature to be described, full protection against corrosive attack with a minimum expenditure of special corrosion-resistant alloy. y

It is an object to provide a section of such a conduit having easily assembled and disassembled parts which sections of the conduit are readily removed and replaced without substantial longitudinal movement and without telesccping, in which ow deectors and baille plates prevent "or minimize by passing of fluid behind thevheat insulation with resultant hot spots in the stress bearing shell, and inl which suitable construction is provided to prevent collapse of the intermediate and inner portions upon pressure fluctuations. f

Numerous other objects and advantages will be apparent to those skilled in the art upon reading the accompanying specification, claims and drawings.

:in the drawing:

The single figure of the drawing is a cross sectional view taken along the longitudinal axis of a high temperature conduit embodying my invention. A

Said high temperature conduit, generally designated as 2, is formed generally as a three element structure comprising a thin walled, unpressured inner conduit 3 formed of a material resistant to high temperatures and preferably resistant to corrosion or oxidation by extremely hot fluids, a concentric outer shell 4 of ordinary structural material, such as low carbon steel, for example,

which will satisfactorily bear the pressure stresses as long as the temperature of the shell is not excessive, and the layer of suitable yheat insulating material interposed between the inner conduit 3 and the outer shell 4 to insure maintenance of the outer shell temperature below the allowable limit. l v

Outer shell 4 may be any pipe suitable for ordinary low temperature conduits. The sections of pipe 4 may be secured together by any well-known means in the practice of the present invention, but as an illustrative embodiment of a preferred form of attaching means, pipes 4 are shown connected by means of flanges 6, studs 1 and nuts 8. While flanges 6 could be secured to pipe 4 by screw threads or other means in the practice of the present invention they are shown secured by welds 9 and II. 'I'he exact form of welds '9 and` Il is not important.

While vflanges 6 may in many instances bev drawn directly together, it is considered good lpractice to provide a suitable gasket I2 between them. Gasket I2 may be made of felted asbestos which may or may not be impregnated with a suitable sealing compound depending on the nature of the uid being transported in the conduit 2, and many such gaskets are for sale for use with various fluids, some of these rgaskets having a thin sheet metal cover (not shown) over the asbestos.

The outer stress bearing shell 4 is of course imperforate. Supported inside shell 4 is an intermediate heat insulating shell 5. 'I'he shell 5 may be cast inplace between shells 3 and 4 in which case the natural bond between the material of shell -5 and shells 3 and 4 serves to reduce the danger of uids bypassing or channeling between shells 3 and 5 or 5 and 4.

However it is contemplated as a modification (not shown) to form shells 3 and 5 in a separate mold of the usual type so that they may be provided as integral preformed interior sections to be inserted when desired in ordinary exterior pipe like 4.

In either modification it is desirable to provide an annular imperforate baille plate I3 sealed to the exteriorshell 4 by suitable means, such as weld I4. In the case of the cast` in place lining 5, baille. I3 will aid in supporting the material during casting, and in the case of the inserted type of liner 5 the liner can be inserted from one end against baille I3 or baille I3 may be placed after liner 5 is inserted.

The ends I8 of inner shell 3 are preferably belled out to aid in the rapid insertion of anged sleeves il. It will be noted that insulating material 5 is removed to form a space I8 allowing room for the expansion and contraction of end I6 of liner 3. This space I3 may be formed when material 5 is cast, or may be removed mechanically thereafter. Y

The specic castable or moldable insulating materials that I have found most suitable in practicing this invention are Panelag, "Insulag and Sil-O-Cell C-3. These are trade names. Quigley Co., 56 West 45th Street, New York city, states Panelag is good for temperatures up lto 1700 F. while Insulag is good up to 2000 F., and that either one when mixed with water forms a plastic'cement material which hardens into an insulating block. Johns-Manville Co., 292 Madison Ave., New York city, states "Sil-O-Cell C-3 is a coarse, granularform of calcined diatomaceous silica, which mixed with water forms a plastic cement which hardens into a block good for temperatures up to 2000 F. The exact composition of Panelag, yIn'sulag and Sil-O-Cell C-3 are secrets, but they are sold by said companies in the open market with directions as to the amount of Water to be added'.

- and the other mixing procedure.

The Refinery CatalogA 1942, Gulf Publishing Company, Houston, Texas, lists suitable inl sulating cements on pages 96, 116, 239, 414, 449, 479, 508, 535 and elsewhere. A mixture of roughly 50% asbestos iibre and 50% Portland cement mixed with just enough water to make it plastic is also suitable, but is not preferred.

In order to provide for the effect of pressure uctuations in conduit 2, a series of breather holes I9 are preferably spaced ina line around the axis of inner shell 3 where the pressure may be transmitted into the porous, lor semiporous, heat insulating material 5, and thus preventing pressure changes on the material with resultant collapse of inner shell 3 and heat insulating material 5.

A stifi'ener ring 2| may be provided in the form of an inwardlyconcave ring around liner-j 3 covering the line of holes I9. 'I'he left side of the drawing being considered as the up-stream side and the right hand side as the down-stream side, (see arrow marked flow), it will be noted the stiffener rings 2I are preferably welded to inthe right half of the drawing is shown a form where ring 2l is continuously welded around the circumference. .Continuous welds of both sides are never employed as then holes I8 would be useless.

In order to keep as much of the high temperature iiuid as possible out of the packing material 5 a nipple 22 may be provided having an outwardly belled end sealed to the interior of said inner shell at a point up-stream of the sleeve I'I, and sleeve 22 may extend down-stream of the up-stream edge of sleeve I 'L Operaltion The operation of the conduit is as follows:

The 'high temperature fluidso far as it retains its high temperature is confined in inner shell 3 which is formed of suitable alloy steel or other alloy material resistant to the high temperature and other conditions existing therein, and parts 3, I1, 2l,V 22 and I3 are preferably made ofsuch Y material. Due to the lack of structural strength of thin inner shell 3, it is impossible/to confine all of the fluid to the interiorof shell 3. However sleeve I1 and nipple 22 are designed to deflect the `1 hot llid Sti-that it will tend stay inside of shell l.

However some of the hot fluid necessarily passes through breather holes Il and some will work its Way into the heat insulating material 5. As

rial 5, or from channeling in heat insulating material I. This channeling is prevented or greatly minimized by baille plate I3. Bama plate I3 is preferably sealed to the outer shell l and extends inwardly to a position overlapping the flanges on sleeve I1. Obviously this construction will bring the iluid back into the central shell 3 so that progressive channeling of large amounts of fluid is rendered unlikely.

If large amounts of hot fluid come in contact with outer shell l by channeling this contact will form hot spots, and these hot spots will cause outer shell l to loose its stress resistance, which may resulty in a dangerous break in the conduit or other accident.

It" will be noted that the flange of sleeve I1 and the end of the outer shell 4, the flanges 6, plate i3, and the ends of heat insulation i all terminate in substantially the same plane transverse to the longitudinal axis of the conduit. portant, as infa long line itmay be desirable to take out one section of the conduit without moving theother sections. With the construction shown. this may be done by merely unbolting studs and nuts 1 and 8 at both ends of the desired section, and removing the section by sliding it out oli' the conduit at right angles to the longitudinal axis without 'substantial longitudinal movement of the remainder of the conduit. Some former insulatedpipes (not shown) are made with telescoping portions, or other construction, in which it would be practically impossible to remove a section of the conduit without an enormous amount of work in moving the two ends of the conduit longitudinallyto permit untelescoping.

lt is believed obvious that I have provided a high temperature conduit capable of carrying out the objects of the invention as enumerated above.

It is understood that while the drawing and descriptive matter of this specification illustrate a, specific example 4wherein my inventionv is of particular benet, other obvious applications can be made. The scope of my invention is therefore subject only tc the' limitation oi' the appended claims.

Having described my invention, I claim:

l. A conduit for high temperature fluids comprising in combination a pipe section comprising an outer imperforate stress-bearing shell, an inner perforated heat resisting shell and an intermediate heat insulating shell, `attachment means comprising flanges secured to each end of said stress resisting shell, means to draw adjacent pairs of said flanges togethens4 gasket between adjacent flanges of adjacent'sections, an annular imperforate bailile plate sealed to said imperforate shell and extending inwardly toward said inner shell, the ends of said inner shell being belled outwardly, a sleeve in each end of said inner This is imwam shell projecting therefrom, the projecting portion of said` sleeve ending in an external imperforate flange extending outwardly to a point overlapping the inward extent of said annular plate, a nipple having an outwardly belled end sealed to the interior of said inner shell at a point upstream oi the sleeve in thev end of said inner shell, said nipple overlapping said sleeve in a downstream direction,` theperforations in said inner perforated shell being spaced in a line around the axis of said inner shell, and a ring exterior of said innershell and spaced to cover all of the perforations in one of said lines, said ring curelald by'welding at its upstream side to the inner she `il. A conduit for high temperature fluids comprising in combination a pipe section comprising an outer imperforate stress-bearing shell, an inner perforated heat resisting shell and an intermediate heat insulating shell, attachment means secured to each end of said stress resisting'shell. an annular imperforate bame plate sealed to said imperforate shell and extending inwardly toward said inner shell, a sleeve in each end of said inner shell projecting therefrom, the projecting portion of said sleeve ending in an externalimperforate flange extending outwardly to a point overlapping the inward extent of saidannularplate, a nipple sealed to the interior of said inner shell at a point upstream of the sleeve inthe end of said inner shell, said nipple overlapping said sleeve in a downstream direction, the perforations in said inner perforated shell being spaced in a line around the axis/'of said inner shell, and a ring exterior of said inner shell and spaced to cover all of the perforations in one of said lines, said ring being secured at its upstream side to the inner shell.l i

3. A conduit for high temperature fluids comprising in combination a pipe section comprising an outer imperforate stress-bearing shell, an inner perforated heat resisting shell and an intermediate heat lnsulating shell, s, sleeve in each end of said inner shell projecting therefrom, the projecting portion of said sleeve ending in an external imperforate flange a nipple sealed to the interior of said inner shell at a point upstream of the 'sleeve in the end ofi said inner shell, said nipple overlapping said sleeve in a downstream direction, the perforations in rsaid inner perforated shell being spaced in e, line around the axis of said inner shell, and a ring exterior of said inner shell and spaced to cover all of the perforations in one oisaid lines, said ring being secured at its upstream side tothe inner shell.

4. A conduit for hig'h temperature fluids comprising in combination a. pipe section comprising an outer imperforate stress-bearing shell, an inner perforated heat resisting shell and an intermediate heatinsulating shell, an annular imperforate baille plate sealed to said imperforate shell and extending inwardly toward said inner shell, a, sleeve in the end of the inner shell projecting therefrom, a nipple sealed to the interior of said inner shell at a, point upstream of the sleeve in the end of said inner shell, said nipple overlapping said sleeve in a downstream direction, the perforations in said inner perforated shell being spacedin a line around the axis of said inner shell, and a ring exterior of said inner shell and spaced to cover all of the perforations in one of said lines, said ring being secured at its upstream side to the inner shell. i.

5. A conduit for high temperature fluids comprising in combination a pipe section comprising an outer imperforate stress-bearing shell, an inner perforated heat resisting shell and an intermediate heat insulating shell, an annular imperforate baille plate sealed to said imperforate shell and extending inwardly toward said inner shell, a sleeve in each end of said inner shell projecting therefrom, the projecting portion of said prising in combination a pipe section comprising an outer imperforate stress-bearing shell, e an vinner heat resisting shell-and-v an intermediate heat insulating shell, anlannular imperforate baille plate sealed vto said imperforate :shell and extending inwardly toward'- said inner shell, Va sleeve in each end of said inner shell projecting therefrom, the projecting portion of said sleeve ending in an external imperforate narige extending outwardly to a point overlappingthe inward extent of said annular plate, and a nipple sealed to the interior of said inner shell at a, point upstream of the sleeve in the end oi said inner shell, said nipple overlapping said sleeve in -a downstream direction.

7. A conduit for high temperature uids co'mprising in combination a pipe section comprising an outer imperforate stress-bearing shell, an inner perforated heat resisting shell and an intermediate heat insulating shell. a sleeve in the end of the inner shell projecting therefrom, a

nipple sealed to the interior of said inner shell at a, point upstream of the sleeve in the end of said inner shell, said nipple overlapping said sleeve in a downstream direction, the perforations in said inner perforated shell being spaced in a line around the axis of said inner shell, and a ring exterior of said inner shell and spaceI to cover all of the perforations in one of said lines, said ring being secured at its upstream side to the inner shell.

8. A conduit for high temperature iiuids comprising in combination a pipe section comprising an outer imperforate stress-bearing shell, an inner heat resisting shell and an intermediate heat insulating shell, ,an annular imperforate bameplate sealed to said imperforate shell and extending inwardly toward said inner shell, and a sleeve in each end of said inner shell projecting therefrom, the projecting portion of said sleeve ending in an external imperforate ange extending outwardly to a point overlapping the inward extent of said annular plate.

9. A conduit for high temperature iiuids comprising in combination a pipe section comprising an outer, imperforate stress-bearing shell, an inner heat resisting shell and an intermediate heat insulating shell, a relatively short sleeve in the end oi' said inner shell projecting therefrom and an annular imperforate baille plate sealed to said imperforate shell and extending inwardly toward but out of contact with said inner shell.

10. A conduit for high temperature iiuids comprising in combination a pipe section comprising an Y outer imperforate stress-bearing shell, an inner perforated heat resisting shell and an intermediate heat insulating shell, an annular lmperforate baille plate sealed to said imperforate shell and extending inwardly toward said inner shell, the perforatlons in said inner perforated `shell being spaced in a line around the axis of said inner shell, and a ring exterior of said inner shell and spaced to cover all of the perforations in one of said lines, said ring being secured to the inner shell.

11. A conduit for high temperature fluids comprising in combination a`pipe section comprising an outer imperforate stress-bearing shell, an inner perforated heat resisting shell and an intermediate heat insulating shell, the perforations in said inner perforated shell being spaced in aline around the axis of said inner shell, and a ring exterior /of said inner shell and spaced to cover all of the perforations in one of said lines, said ring being secured to the inner shell.

LOUIS JOE WEBER.

REFERENCES C ITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

